Xee

Xee is an acceptable alternative to Preview that allows you to view practically any image stored on the hard drive. As an image viewer, it offers basic editing functions, such as rotate, cut, and zoom. In addition, it supports a large amount of image formats and allows you to convert between formats. The types of file formats that Xee can process are: JPEG, PNG, GIF, TIFF, PSD, RAW, CR2, MRW, ...